The interests and proposed course of the Biologic Structure Section is to characterize the role of the macrophage in antigen recognition by T lymphocytes in the expression and initiation of cell mediated immunity in man and experimental animals. In addition, we are interested in exploring the role of histocompatibility and genetic regulation in cell-cell interactions required for expression of cell mediated immunity. The Biologic Structure Section is also actively characterizing the physical state of, localization, and fate of macrophage associated in in vitro antigen mediated lymphocyte proliferation and determining if genetic control of the immune response to insulin exists in man.